You'll have to check your notebook manual for specific details for your
particular make and model but in general, connect it to the monitor port on
the back of the notebook, then turn it on and then reboot the notebook.
Right click on the Desktop and select Properties... then select Advanced...
and you should now find you have two monitors listed (one being the notebook
one and the other being the external one)... you can choose to switch output
from one to the other, to clone the notebook (and therefore have the same on
both) or to extend the monitor (half on one screen, half on the other).